linux-kernel - Re: [PATCH] ARM: mm: Facilitate debugging CONFIG_KUSER

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Message-ID: <a48601e2-dde2-47b8-b591-ffccdc9f1bf8@gmail.com>
Date:   Thu, 25 Oct 2018 11:50:43 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-arm-kernel@...ts.infradead.org, andrew@...n.ch,
        Russell King <linux@...linux.org.uk>,
        Tony Lindgren <tony@...mide.com>,
        Souptick Joarder <jrdr.linux@...il.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: mm: Facilitate debugging CONFIG_KUSER_HELPERS
 disabled

On 10/25/18 11:25 AM, Eric W. Biederman wrote:
> Florian Fainelli <f.fainelli@...il.com> writes:
> 
>> Some software such as perf makes unconditional use of the special
>> [vectors] page which is only provided when CONFIG_KUSER_HELPERS is
>> enabled in the kernel.
>>
>> Facilitate the debugging of such situations by printing a debug message
>> to the kernel log showing the task name and the faulting address.
> 
> Can't someone trigger this segv deliberately and spam the kerne log?
> Doesn't this need something like printk_ratelimit or something to ensure
> this message only gets printed once?

Yes, good point, thanks.
-- 
Florian